Effects of Light, Growth Media, and Seedling Orientation on Bioassays of Alfalfa Autotoxicity

Abstract

Guenzi et al., 1964; McCalla and Haskins, 1964; Klein and Miller, 1980; Jensen et al., 1981; Jennings and Nel-Most assessments of allelopathy involve bioassays. Our objective son, 1998), but the causative chemical(s) have not been was to improve the sensitivity of an alfalfa (Medicago sativa L.) seedling bioassay for evaluating genetic tolerance to autotoxic leaf unequivocally identified. Autotoxicity in alfalfa may reextracts. In a petri dish assay on imbibed seed, light inhibited hypocotyl sult from an interaction of more than one chemical elongation of controls and increased root elongation. Root growth present in the shoot, especially in the leaves (Chung was sensitive to the autotoxin in both light and darkness. An agar and Miller, 1995). medium gave better root growth of controls and lower standard errorsMost assessments of allelopathy or autotoxicity inthan did filter paper when petri dishes were placed on edge to encourvolve bioassays of plant or soil extracts based on seed age downward root growth or were placed flat where roots grew germination or seedling growth. Generally, germination laterally. Hypocotyl growth was not very sensitive to the autotoxic

Allelopathic Performance of Medicinal Plants on Traditional Oilseed and Pulse Crop of Central Himalaya, India

“…These results are in agreement with the results of Stachon and Zimdel [19] which reported that the extracts of allelopathic plants had more inhibitory effect on root growth than on hypocotyl growth because root is the first organ to absorb allelochemical from the environment. Similar kinds of results were reported from the studies of Chon et al [20] in which root length was the best indicator of allelopathic effects of plant extract because root growth has been reported to be more sensitive to phytotoxic compounds than hypocotyl growth in alfalfa. Based on the results of the present study it could be suggested that the four medicinal plants species can be grown satisfactorily under traditional agriculture systems of subtropical-sub temperate region if whole plants of these medicinal species are harvested from the agricultural fields and nothing is left in the fields for allelopathic influence.…”

“…These results are in agreement with the results of Stachon and Zimdel [19] which reported that the extracts of allelopathic plants had more inhibitory effect on root growth than on hypocotyl growth because root is the first organ to absorb allelochemical from the environment. Similar kinds of results were reported from the studies of Chon et al [20] in which root length was the best indicator of allelopathic effects of plant extract because root growth has been reported to be more sensitive to phytotoxic compounds than hypocotyl growth in alfalfa.…”

Efeito alelopático de folhas de Solanum lycocarpum A. St.-Hil. (Solanaceae) na germinação e crescimento de Sesamum indicum L. (Pedaliaceae) sob diferentes temperaturas

“…1). A ausência de efeitos alelopáticos na germinabilidade foram previamente descritos para sementes de Mimosa bimucronata (Ferreira & Aquila 2000) e de alfafa (Medicago sativa) (Chon et al 2000), sendo corroborados no presente trabalho.…”

“…Em diversos casos também se observou desenvolvimento incompleto da coifa e inversão no gravitropismo das raízes por efeito dos extratos. A inversão do gravitropismo foi também observada no efeito autotóxico da alfafa (Chon et al 2000). Segundo os autores, seria uma forma de evitar o contato com os aleloquímicos.…”

“…De forma geral, as raízes mostraram-se mais sensíveis à ação do(s) aleloquímico(s) comparada com a parte aérea, o que já foi relatado por diversos autores (Chon et al 2000;Ferreira & Áquila 2000;Batish et al 2002). Enquanto a parte radicular foi inibida cerca de 75% a 22 o C, a parte aérea chegou no máximo a 35% de inibição, na mesma concentração utilizada.…”